Recently, the control mechanisms of hair growth and hair loss have been elucidated, while a variety of new hair growth agents such as novel compounds having the hair growth-promoting effect, ingredients based on genetic research, combinations of the Chinese traditional medicine system and others have been proposed along with increased public concern for hair growth agents.
FIG. 1 is an illustrative diagram showing a hair cycle that repeats hair growth and hair loss. A normal hair has a hair papilla 3 in a hair root 2 of a hair body 1 thereof and has a trichogen cell 4 above the hair papilla 3. The hair body 1 grows up, enters a regression phase (catagen) and stops growing in approximately 2 to 3 weeks. Then, it enters a resting phase (telogen) for 2 to 3 months. In the meantime, the hair root 2 continues its activities and generates a new hair body 1′. This new hair body 1′ proceeds to enter a growth phase (anagen) and loses the old hair body 1. It further keeps growing and regenerates an original hair form in approximately 5 to 6 years.
Hair growth agents have the effect of promoting trichogen cell growth in each phase of such a hair cycle, inducing the anagen phase in the telogen phase, prolonging the anagen phase, or delaying shift to the catagen phase and perform the promotion of hair growth or the inhibition of hair loss.
For example, a hair growth agent comprising 6-(1-piperidinyl)-2,4-pyrimidinediamine-3-oxide (minoxidil) as an active ingredient (see U.S. Pat. No. 4,139,619), a hair growth composition comprising 1 to 6% by mass of minoxidil, polyhydric alcohol, ethanol, pyridoxin hydrochloride, and water (see Japanese Patent Laid-Open No. 2002-326913), a hair growth agent comprising a fibroblast growth factor-10 (FGF-10) as an active ingredient (see Japanese Patent Laid-Open No. 10-279501), a pilatory comprising particular fatty acid ester, ether, monoglyceride sulfate, or monoalkyl glyceryl ether sulfate as an active ingredient (see Japanese Patent Laid-Open No. 11-246359), a hair growth agent comprising a CRF1 receptor antagonist as an active ingredient (see the pamphlet of International Publication No. WO 02/019975), an aerosol preparation for hair growth containing: a gelled composition for aerosol comprising a crude drug extract with blood circulation-promoting effect and vitamin or a derivative thereof as active ingredients and having a water-soluble polymer mixed therewith; and a propellant (see Japanese Patent Laid-Open No. 7-101834) and elsewhere have previously been proposed as such hair growth agents.
Alternatively, an oral hair growth agent comprising, as an active ingredient, a peptide represented by the formula, R1-Met-Ile-XR2 (in the formula, X represents Trp, Phe, Trp-Leu, Phe-Leu, Tyr-Leu, Ile-Leu, or Leu-Leu; R1 represents a hydrogen atom or an amino-protecting group; and R2 represents a hydroxyl- or carboxyl-protecting group) or a pharmacologically acceptable salt is known as a special hair growth agent (see the pamphlet of International Publication No. WO 00/29425).
In addition, information from very recent newspaper has reported the release of a hair growth agent having 6-benzyl aminopurine (cytopurine) in combination with pentadecane (see the article issued on Mar. 2, 2004, Nikkei Business Daily).
These hair growth agents have their own advantages, and some of them are approved to exhibit significantly effects. However, they cannot completely respond to all symptoms and certain raw materials thereof are difficult to obtain so that they are not necessarily adequate for practical applications. Therefore, the appearance of a novel hair growth agent exhibiting excellent effects has been demanded in this field.
On the other hand, a skin lotion for anti-aging consisting of a polymerization product with an average molecular weight of 280 to 20000 of a tripeptide composed of one glycine residue and two other amino acid residues in a degradation product of collagen or gelatin obtained by collagenase (see Japanese Patent Laid-Open No. 2000-309521), a collagen-producing promoter comprising a mixture of tripeptides consisting of (Gly-Ala-Arg), (Gly-Ala-Hyp), (Gly-Ala-Lys), (Gly-Pro-Ala), (Gly-Pro-Arg), (Gly-Pro-Hyp), and (Gly-Pro-Ser) as an active ingredient (see Japanese Patent Laid-Open No. 2003-137807) and elsewhere are known as physiologically active substances comprising an oligopeptide or a polymerization product thereof as an active ingredient. However, no epithelial cell growth promoter comprising a tripeptide as an active ingredient has been proposed so far.